PUNE: A recent study by city-based Ela Foundation and MESAbasahebGarware College, to assess the impact of wind farms on birds at the Bhambarwadi Plateau in the northern Western Ghats, found 27 bird species out of 89 at the risk of collision with the rotor blades of the wind turbines.

Out of the 12 birds (belonging to seven species) that were found dead, five were raptors belonging to three different species. Also, out of five Indian endemic bird species observed in the study area, the Malabar Crested Lark (endemic to the Western Ghats) was recorded in the risk zone. The study also reported a reduction in the birds in the study area due to the increasing wind farm construction and associated infrastructure development. But the drop in the number of birds in the region is gradually reducing.

Researchers recorded 27 bird species flying in the risk zone, out of which 11 were raptors. “Raptors are at a higher risk of collision as compared to other species. Such high risk of raptor collisions with turbine rotors and overhead power lines has been earlier reported by studies abroad,” he said.

Ornithologist Satish Pande of Ela Foundation said the collision index (the number of bird collisions with the wind turbines over a period of one year, assuming the birds do not take any avoidance measures) for these species was estimated. “We also identified the species which are at a risk of collision with the turbines with the help of transformers, wind-masts and electrocution. Reduction in avian activity in the study area was noticed with the increase in the number of wind farms. Despite the small footprint of an individual wind turbine, the associated infrastructure development causes a wider habitat modification and destruction, resulting in a displacement effect for the birds,” said Pande.

The research titled ‘Avian collision threat assessment at ‘Bhambarwadi Wind Farm Plateau in northern Western Ghats, India’, was recently published in the Journal of Threatened Taxa. It also suggested that the wind farm erections in strategic locations such as biodiversity hotspots should be subject to prior site based strategic environmental assessments (SEA) and environmental impact assessment (EIA) studies. Other researchers include Anand Padhye of MES Abasaheb Garware College, Pramod Deshpande, Aditya Ponkshe, Pranav Pandit, Amit Pawashe, Shivkumar Pednekar, Rohan Pandit and Prashant Deshpande.

Padhye added that the study area is situated on the Bhambarwadi Plateau on the northern Western Ghats or the Sahyadri mountains.

“There was a proposal to construct 13 wind turbines in the study area, where ten wind turbines were previously constructed. The Chandoli Wildlife sanctuary is approximately five km to the west of the study area, which is a high level rocky plateau on the Sahyadris,” said Padhye.

Parameters such as the bird species, the number of individuals of each species flying in the study area, whether the bird was flying in the risk zone, below it or above it, total flight time of each species in minutes (flight activity) and the flight activity of birds in the risk zone (risk activity) were recorded. Risk zone is the region between the lowest and the top most points swept by the rotor blades.

Pande said that out of 1,604 minutes of the total bird flight activity, flight activity in the risk area was 1,067 minutes. “Seasonal flight activity in the risk area showed the same trend with maximum flight activity in the risk area during summer followed by monsoon,” he said.

In addition to the risk zones created by the turbines, Pande said that the wind masts were earlier supported by very thin steel wires that were not visible from a distance, and led to bird collisions and subsequent mortality. “Now the thin wires have been replaced by steel guy ropes that are more visible,” he said.

During the study period of two years, 19 birds and mammals were found dead due to collision with the rotor blades or electrocution due to contact with over-head transmission lines or transformers. Asian Palm Civets were found dead in the transformers built for transmitting windmill power to the base stations. “Swallows and martins were found dead in post monsoon period. In addition, we also noticed that two black kites and one changeable hawk eagle collided with wind masts,” said Pande.

In addition, the researchers calculated the hypothetical collision probability of all the 27 bird species flying in the risk zone swept by the rotor blades.

“Assuming that the birds do not take any preventive action so as to avoid collision with the blades, the yearly average collision rate was 1.9 birds per turbine. Considering the presence of 13 wind turbines in the study area, the total collision rate is 24.9 birds annually. However, the collision avoidance measures taken by birds are almost 95%,” said Pande.

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